The invention relates to a bi-directional incoming air flow fan and, more particularly, a bi-directional incoming air flow fan used in a computer assembly to dissipate heat.
Electrical fans are usually used to create an air flow and commonly provide the possibility of changing the outputted air flow direction. Electrical fans can be differentiated from their directions of air flow input and output. Such a differentiation principally leads to a distinction between axial flow type fans and centrifuge type fans. Axial flow type fans have the characteristics of generating an incoming air flow from the rotation axis of the rotary blades, the air flow then is compressed and outputted along the same rotation direction. In contrast, centrifuge type fans generate an axial incoming air flow that is outputted along the radial direction of the rotary blades.
Centrifuge type fans are traditionally known as blowers, and are usually comprised of a case and a rotor mounted in the case. It is further common that the case includes an axial face that has an air inlet and a radial face that has an air outlet. The rotor includes a plurality of rotary blades that, once put in rotation, generate an incoming air flow from the air inlet axially disposed, and an outgoing air flow through the air outlet.
Because a single face of the above traditional fan is provided with an air inlet, higher air flow amount therefore cannot provided. The prior art thus also provides a centrifuge type fan having a bi-directional incoming air flow. In this type of known fan, two axial faces of the case are respectively provided with an air inlet. However, because the air inlets do not have an equal surface area, incoming air flows are therefore not symmetrical when the rotor rotates, which causes deviation and generation of a floating force or compressive force to which the rotor is negatively subjected to. This results in an increase of friction and vibration of the rotor, which affects the life service of the fan and further generates parasitic noise.
It is therefore a principal object of the invention to provide a centrifuge type fan with bi-directional incoming air flow that can achieve a uniform incoming air flow from two sides, thereby reducing a deviation of the rotor and mechanical frictions due to a floating force, while providing a higher amount of air flow output.
To accomplish the above and other objectives, a bi-directional incoming air flow fan of the invention comprises a case in which is mounted a rotor that includes a plurality of rotary blades. The case has top and bottom faces that are respectively provided with a first and second air inlet having approximately a same surface area. A side of the case is further provided with an air outlet. Furthermore, each rotary blade includes an upper and lower sides that respectively have an axial flow guiding rib, and a free section that is inclined to form a radial flow section. Thereby, once the rotor is put in rotation, air flow amount and pressure are increased by means of the axial flow guiding ribs that create an uniform air flow. As a result, rotor deviation and floating force are reduced, thereby reducing mechanical frictions and parasitic noise.